Practical Sailor in a recent article on heads and marine plumbing, described a sanitation system designed by Dometic where check valves in strategic locations took the place of vented loops. This is an appealing concept, as it would reduce the volume of waste that would invariably be left sitting in the hoses due to the height of the vented loop and the added overall length of the hoses. Has anyone built a sanitation system in this fashion? And what does Peggy think of this concept?
Check valves vs vented loops
- Thread starter David Popken
- Start date
I suspect you're confusing apples and oranges...'cuz a joker valve in a marine toilet is one type of check valve...so are the "duckbill" valves in a VacuFlush system, which is now owned by Dometic. They also use check valves as a "pressure relief" valve in one or more of their holding tank systems, including a disaster they call the "Sailvac," which is the worst idea EVER! A vented loop is a siphon break, which has an entirely different function from a check valve.
If you still have the iissue that includes that article, I'd like to read it. 'Cuz till I know exactly what they're talking about I can't comment. Can you scan it and attach it to an email to me?
If you still have the iissue that includes that article, I'd like to read it. 'Cuz till I know exactly what they're talking about I can't comment. Can you scan it and attach it to an email to me?
Can you comment on the sailvac system and the problems? I am not super happy. In the last 12 months I have had a system that would not flush at all after initial commissioning, then vacuum leaks through the bowl seal twice, and liquid leaks. Also due to the way they are vented I need to be present for any pump outs.
Practical Sailor Article
Here is the link:
http://www.practical-sailor.com/iss...Plumb_Thee_Let_Us_Count_the_Ways_10148-1.html
Peggy,
Here is the link:
http://www.practical-sailor.com/iss...Plumb_Thee_Let_Us_Count_the_Ways_10148-1.html
Of course, keep flushing, but if the line is 12' long, that's alot of strokes every time someone uses the head, and in no time at all, the holding tank is full, so for me, keep flushing is not an option.
Sailvac system issues
It combines the VacuFlush vacuum tank with the holding tank, which means the holding tank cannot be vented because a vented tank can't hold the vacuum requred by the VacuFlush. So you're stuck with an anaerobic tank that has only a "pressure relief" valve that only opens to allow the tank be pumped out. If the pressure relief valve sticks in the closed position, the tank can't be pumped out because the pump will pull a vacuum. If it sticks in the open position, the Vacuflush can't achieve the vacuum needed for the toilet to work. Even when it all works as it's supposed to, the anaerobic conditions in the tank result in horrible odors that escape through the bowl. As I said previously, it has to be the worst idea anyone has ever dreamed up.
Unfortunately, only paid subscribers to PS can read past the promo first paragraph of the article...and I'm no longer a paid subscriber. It would be a bit of a PITA for you to scan and save it to attach to an email, but I'd really appreciate it!
Here is a scanned copy. Btw, they mention you and your book, which I have recently bought and read. I am completely re-fitting the sanitation system on our Sabre 38. After 27 years, the hoses were beyond odoriferous. Sabre did have vented loops, and I can replace them with the new hoses if indeed that is what should be done. Also, I have up sized the tank vent to 1", but have not found any 1" thru hull vents to terminate with.
David
How Do We Plumb Thee.pdf
David
How Do We Plumb Thee.pdf
David
Have you really looked?
http://www.westmarine.com/buy/forespar--marelon-mushroom-heads-threaded--P011_332_002_513
This is what you need, not a standard vent, because they have screens in them. If you put it up high on the topsides it won't ingest any water.
Head Odors 101.3 Flix of New Vent http://c34.org/bbs/index.php/topic,8185.msg57288.html#msg57288
Head Pumps 101 Why just pouring water into the bowl is NOT a good idea http://c34.org/bbs/index.php/topic,5865.msg40604.html#msg40604
Hmmmmmmmmm ............................
If you look at the exploded view of a Jabsco in DRY position, there will always be a couple of inches of water above the piston as it slops back and forth through the forced open discharge valve. As long as you've got any water above the piston, you're not going to get additional wear.
I can attest to this #$@^%>&%*! condition as I always try to remove all water possible from above the piston when I am stuck with removing and lubricating the piston ring. There's always a few inches of water remaining above the piston which manages to spill down the front of your shorts :cussing:.
....................... gotta wonder about that one for a Jabsco head, Stu.
If you look at the exploded view of a Jabsco in DRY position, there will always be a couple of inches of water above the piston as it slops back and forth through the forced open discharge valve. As long as you've got any water above the piston, you're not going to get additional wear.
I can attest to this #$@^%>&%*! condition as I always try to remove all water possible from above the piston when I am stuck with removing and lubricating the piston ring. There's always a few inches of water remaining above the piston which manages to spill down the front of your shorts :cussing:.
Attachments
I thought I needed a screen on the vent, not just a mushroom thru hull. If vented on deck, I would worry about a foreign object falling into it and blocking the vent. If vented thru the hull, it would still worry me that wasps or other pests might decide to nest inside.
Why would you even consider venting out the deck? Vent out the hull! And you've just made the case for back flushing the vent line every time you wash the boat and/or pump out. "Vent" thru-hulls don't allow you to do that, plus they don't allow enough air exchange...screens create more problems than they prevent...they rust, clog up with dust and pollen and clog up even quicker if the tank overflows out the vent. 30 seconds with a hose nozzle up against an open thru-hull while washing th boat is all it takes to keep the vent line open.
Removing the piston o-ring to lubricate just it and nothing else is mostly an exercise in futility because it doesn't put enough grease in the pump last more than 15 minutes...you might as well just flush a shot of vegetable oil. If you want a lube job to last a full season AND stay dry while you do it, buy a tube of SuperLube thick Teflon grease, take the top off the pump. Stick the tube nozzle into the pump and give it a healthy squirt. Pump a couple of times to spread it all over the inside of the pump cylinder wall...put the top back on the pump...you're done till next spring.
"As long as you've got any water above the piston, you're not going to get additional wear."
If water were all that's need to keep a pump lubricated and prevent wear, why do pumps need grease?
Just repeating what you originally said back in 2011:
Head Pumps 101 Why just pouring water into the bowl is NOT a good idea http://c34.org/bbs/index.php/topic,5865.msg40604.html#msg40604
And btw..keeping the intake seacock closed all the time and flushing only by pouring water into the bowl is VERY bad for the pump because bowl contents only go through the bottom part of the pump...leaving the top half of the pump dry all the time, which wears out the rubber parts a lot faster. Replumb it to tee it into the sink drain line and operate your toilet as it was designed to be operated.
Makes sense, thank you. I haven't had problems with the valve or odors yet, but just recently it started to not be able to keep the vacuum longer than an hour or two, perhaps the valve is acting up. In general I am concerned about all the potential maintenance.
At the risk of possibly hyjacking...
Please Peggy with your brains and knowlege of plumbing, there must be a way of connecting to the boats fresh water tanks. Read your book about using the sink but that requires quests understand and remember, and as my shower sump is teed into the drain would need more valves than would fit.
Please Peggy with your brains and knowlege of plumbing, there must be a way of connecting to the boats fresh water tanks. Read your book about using the sink but that requires quests understand and remember, and as my shower sump is teed into the drain would need more valves than would fit.
Larry, you simply don't want to do that. The reason is that you could contaminate your fresh water supply.
As far as using the sink, you only use that as the LAST flush of the day, because it serves to clean the salt water out of the inlet hose and the little holes inside the kip of the bowl.
Otherwise, use sea water, and your guests will know nothing different than simply using the head.
Peggie has contributed to these posts:
Head Odors 101 http://c34.org/bbs/index.php/topic,5755.0.html
Head Odors 101.1 - "T" into sink drain: http://c34.org/bbs/index.php/topic,5755.msg38216.html#msg38216
Head Pumps 101 Why just pouring water into the bowl is NOT a good idea http://c34.org/bbs/index.php/topic,5865.msg40604.html#msg40604
As far as using the sink, you only use that as the LAST flush of the day, because it serves to clean the salt water out of the inlet hose and the little holes inside the kip of the bowl.
Otherwise, use sea water, and your guests will know nothing different than simply using the head.
Peggie has contributed to these posts:
Head Odors 101 http://c34.org/bbs/index.php/topic,5755.0.html
Head Odors 101.1 - "T" into sink drain: http://c34.org/bbs/index.php/topic,5755.msg38216.html#msg38216
Head Pumps 101 Why just pouring water into the bowl is NOT a good idea http://c34.org/bbs/index.php/topic,5865.msg40604.html#msg40604